EP2056527A1 - Frequency band selection in a telecommunications network - Google Patents

Abstract

The method involves measuring signal power received in frequency bands by determining maximum signal power received in each frequency band. A set of parameters is associated with the frequency bands, where each parameter is determined according to the maximum signal power. Scores are allocated to the frequency bands based on the parameters associated to the frequency bands and to other frequency bands partially superimposed with the bands. The frequency band with minimum score is selected based on the scores allocated to the frequency bands. Independent claims are also included for the following: (1) a device for selecting a frequency band in an access point of a telecommunication network (2) a computer program comprising a set of instructions for implementing a method for selecting frequency band in an access point of a telecommunication network (3) a recording medium comprising a set of instructions for implementing the method for selecting frequency band in the access point of the telecommunication network.

Description

The present invention relates to a frequency band selection in a telecommunications network having a plurality of partially superimposed frequency bands.

More particularly, it relates to a frequency band selection for an access point of a wireless WiFi network ("Wireless Fidelity").

Generally, an access point of a WiFi type wireless network deployed on a particular type of market, professional or community, transmits signals in a single frequency band that is determined prior to the installation of the access point. and regardless of the radio usage conditions. However, the performance of the access point is improved if the operation of the access point depends on the radio conditions.

In the state of the art, there are algorithms allowing the access point to automatically select a frequency band for transmitting signals.

Some algorithms measure a total power received in each frequency band available to the access point and select the frequency band for which the total power received is minimal and in which at least a large number of access points transmit signals.

These algorithms have the drawback of not considering interference other than that generated by WiFi type signals and recoveries between adjacent frequency bands.

• une association de paramètres respectivement aux bandes de fréquence, chaque paramètre étant déterminé en fonction de la puissance maximale de signal reçu dans la bande de fréquence respective,
• une attribution de scores à au moins quelques unes des bandes de fréquence, un score étant attribué à une bande de fréquence en fonction des paramètres associés à ladite bande de fréquence et aux bandes de fréquence partiellement superposées à ladite bande de fréquence, et
• une sélection de la bande de fréquence ayant un score minimal par rapport aux scores attribués aux bandes de fréquence.

To overcome the disadvantages mentioned above, a method according to the invention for selecting a frequency band in a telecommunications network having several partially superposed frequency bands, comprising a measurement of at least one power of a signal received in each frequency band is characterized in that the measurement comprises a determination of a maximum received signal power in each frequency band, and in that the method comprises the following steps:

• an association of parameters respectively with the frequency bands, each parameter being determined as a function of the maximum signal power received in the respective frequency band,
• assigning scores to at least some of the frequency bands, a score being assigned to a frequency band according to the parameters associated with said frequency band and the frequency bands partially superimposed on said frequency band, and
• a selection of the frequency band having a minimum score compared to the scores assigned to the frequency bands.

According to the invention, the best available frequency band for coverage and performance of the telecommunications network is automatically selected using available measurements existing in the network, after a scan of the frequency bands available to the network. For example, the frequency band is selected in order to be allocated to a channel of communication for transmitting and receiving signals in a wireless local area network.

The invention makes it possible to select the frequency band that offers the best bit rate performance for a given radio environment, taking into account interference signals in the frequency band and in the frequency bands adjacent thereto. In this respect for defining the radio environment, the parameter associated with a respective frequency band may depend on the largest of the identifiable jammer signal strengths received in the respective frequency band. An identifiable jammer signal is for example the beacon path of an access point included in the telecommunications network, or an access point or a base station in another network adjacent to said telecommunications network.

According to another characteristic of the invention, a noise power can be determined for each frequency band. In a first embodiment, a score may be assigned only to each frequency band whose determined noise power is less than a threshold. In a second embodiment, a score may be assigned to each frequency band, and the selected frequency band with the minimum score in relation to the assigned scores has a determined noise power below a threshold.

The frequency band selected by the device has the minimum score and a noise power below the threshold. In the first embodiment, only the frequency bands for which the noise power is lower than a threshold are retained during the determination of the score. In the second embodiment, all the frequency bands are considered during the score determination and the noise power determined for the frequency band having the minimum score is compared with the threshold in order to select this frequency band if the noise power is below the threshold.

According to another characteristic of the invention, the parameters respectively associated with the frequency bands may be respectively weighted by coefficients for assigning a score to each frequency band, each coefficient associated with a frequency band depending on a frequency maximum rate in the frequency band to which the score is awarded in the presence of interference signals in the frequency band with which the coefficient is associated with a maximum rate in the frequency band to which the score is awarded in the absence of jamming.

The score assigned to a frequency band therefore depends on the receiving radio characteristics of the device in the frequency band.

According to another characteristic of the invention, the parameter associated with a frequency band may be weighted by a number of equipment transmitting signals in said frequency band for assigning a score to said frequency band.

The score assigned to a frequency band then takes particular account of the equipment that can jam the signal transmitted by the device in the frequency band that can be selected.

According to another characteristic of the invention, the frequency bands can have frequencies respective central units spaced from each other by the same frequency interval and the same bandwidth. The number of frequency bands partially superimposed on a frequency band may be substantially equal to twice the ratio of the frequency bandwidth over the given frequency interval. The invention is particularly suitable for the automatic selection of frequency band in a WiFi type wireless network having frequency bands of the same bandwidth and regularly distributed around a frequency of the order of a few gigahertz.

• un moyen pour associer des paramètres respectivement aux bandes de fréquence, chaque paramètre étant déterminé en fonction de la puissance maximale de signal reçu dans la bande de fréquence respective,
• un moyen pour attribuer des scores à au moins quelques unes des bandes de fréquence, un score étant attribué à une bande de fréquence en fonction des paramètres associés à ladite bande de fréquence et aux bandes de fréquence partiellement superposées à ladite bande de fréquence, et
• un moyen pour sélectionner la bande de fréquence ayant un score minimal par rapport aux scores attribués aux bandes de fréquence.

The invention also relates to a device for selecting a frequency band in a telecommunications network having a plurality of partially superimposed frequency bands, comprising means for measuring at least one power of a signal received in each frequency band, characterized in that that the means for measuring is able to determine a maximum signal power received in each frequency band, and in that the device comprises:

• means for associating parameters respectively with the frequency bands, each parameter being determined as a function of the maximum signal power received in the respective frequency band,
• means for assigning scores to at least some of the frequency bands, a score being assigned to a frequency band according to the parameters associated with said frequency band and the frequency bands partially superimposed on said frequency band, and
• means for selecting the frequency band having a minimum score compared to the scores assigned to the frequency bands.

Finally, the invention relates to a computer program adapted to be implemented in a device for selecting a frequency band, said program comprising instructions which, when the program is executed in said device, perform the steps in accordance with FIG. method of the invention.

• la figure 1 est un bloc-diagramme schématique d'un dispositif pour sélectionner une bande de fréquence dans un réseau de télécommunications selon l'invention ; et
• la figure 2 est un algorithme d'un procédé pour sélectionner une bande de fréquence selon l'invention.

Other characteristics and advantages of the present invention will emerge more clearly on reading the following description of several embodiments of the invention given by way of non-limiting examples, with reference to the corresponding appended drawings in which:

• the figure 1 is a schematic block diagram of a device for selecting a frequency band in a telecommunications network according to the invention; and
• the figure 2 is an algorithm of a method for selecting a frequency band according to the invention.

The figure 1 shows functional means included in a communication device DC for implementing the method of the invention in a telecommunications network RT.

For example, the telecommunications network RT is a WLAN type wireless local area network (WLAN) wireless radiocommunication network complying with one of the standards 802.11 (b, g, a, n), for example satisfying the WiFi label. In another example, the telecommunications network RT is a wired telecommunication network with frequency multiplexing.

The telecommunications network RT has several frequency bands partially superimposed. Each frequency band contains at least one frequency in common with at least one other frequency band.

For example, in a WiFi network, an access point has N = 13 frequency bands distributed in a frequency band between approximately 2.4 GHz and approximately 2.5 GHz, for example having an equal bandwidth. at 20 MHz. The frequency bands each have a bandwidth of about 20 MHz and have respective center frequencies spaced two by two within the same given frequency range of about 5 MHz and for example equidistributed in a frequency interval of about 100 MHz. In general, the number of frequency bands partially superimposed on a given frequency band is twice the integer value of the ratio of the frequency bandwidth over the given frequency interval.

According to the preceding example, a given frequency band BF _n , with 1 ≤ n ≤ N, is thus partially superimposed on at most eight adjacent frequency bands. For example, a given frequency band BF _n , with 5 ≤ n ≤ 9, is partially superimposed on four adjacent frequency bands BF _n-4 to BF _n-1 having center frequencies lower than the center frequency of the frequency band given and four adjacent frequency bands BF _{n + 1} to BF _{n + 4} having center frequencies above the center frequency of the given frequency band.

The communication device DC is for example included in an access point in a wireless digital radio network. In particular, features of the DC device can be implemented in the access point processor driver.

In the device DC are only represented functional blocks, most of which provide functions related to the invention and may correspond to software and / or hardware modules.

The DC device comprises an MRP power receiving module, a MEV evaluation module and an MSB frequency band selection module.

The device DC is able to transmit and receive signals in a selected frequency band to at least one client terminal TC in the telecommunications network RT.

According to an exemplary embodiment with reference to the figure 1 , the telecommunications network RT is a WiFi wireless digital radio communication network. In order not to overload the figure 1 only two TC client terminals have been shown which are a mobile cellular radio terminal and a communicating personal digital assistant.

The TC client terminals and the RT telecommunications networks are not limited to the above examples and may be constituted by other known terminals and networks.

In the telecommunications network RT there may be present telecommunications equipment which transmits signals, hereinafter called signals of scrambling, scrambling the signals transmitted or received by the DC device. Such equipment is designated hereinafter by scramblers BR which themselves broadcast interference signals in frequency bands partially superimposed or close to the frequency band used by the DC device.

Scramblers can be classified into two categories depending on whether they are identifiable or not. In the first category, a jammer BR1 is identifiable and can be of the same type as the DC device; for example, the scrambler BR1 is included in another access point of the digital wireless radiocommunication network RT to which the access point including the DC device belongs, or in an access point of a digital radiocommunication network wireless network neighbor RT, or even in a device transmitting signals of the same nature as those issued by the DC device, as a base station in a network type UMTS ("Universal Mobile Telecommunications System" in English). The jammers of the first category are identifiable by beacons whose frequencies are known by the DC device. In the second category, a scrambler BR2 can be an unknown transmitter of the DC device and emits a signal whose frequency band is spread in at least one of the frequency bands BF _n-4 to BF _{n + 4} allocated to the network. RT. The scrambler BR2 is for example a video transmitter in a video recorder which is capable of transmitting analog display signals to a neighboring television.

For example, the DC device is included in an access point of a WiFi network under the cover of which a BR1 scrambler is located. is an access point of another WiFi network and a scrambler BR2 which is a video transmitter broadcasting 2.4 GHz signals. The device DC as part of a WiFi access point is connected for example to a modem at the end of a line of the type DSL ("Digital Subscriber Line" in English) to serve at least one terminal TC client by wireless link and, if necessary, a wired link client terminal.

With reference to the figure 2 the method according to the invention comprises steps E1 to E 6 executed automatically in the communication device DC and implemented by instructions of a computer program recorded on a recording medium readable by the communication device DC . The device DC is hereinafter considered for example as included in an access point of a WiFi type network having N = 13 frequency bands BF _n , with 1 ≤ n ≤ N, each frequency band BF _n being partially overlapping at most eight adjacent frequency bands.

At an initial step E0, coefficients A _n-4 to A _{n + 4} are respectively associated with bands of frequency BF _n-4 to BF _{n + 4} and specific to a given frequency band BF _n . Each coefficient A _n-4 to A _{n + 4} associated with a frequency band considered BF _n-4 to BF _{n + 4} is constant regardless of the given frequency band BF _n . Each coefficient A _n-4 to A _{n + 4} depends on the ratio of the maximum bit rate obtained with the given frequency band BF _n in the presence of interference signals emitted by jammers BR1 in each frequency band BF _n-4 to BF _{n + 4} on the maximum rate obtained with the given frequency band BF _n in the absence of jamming signals. For example, for a given frequency band BF _n , the coefficient A _n-1 relative to the adjacent frequency band BF _n-1 depends on the ratio of the maximum bit rate obtained with the frequency band BF _n in the presence of jamming signals in the band of adjacent frequency BF _n-1 on the maximum rate obtained with the given frequency band BF _n in the absence of interference signals.

These coefficients depend on the performance of transmission rates which are relative to each frequency band and specific to the DC device. A coefficient associated with a frequency band adjacent to a given frequency band represents the reception quality of a signal in said given frequency band when a scrambler transmits signals in said adjacent frequency band. The previous flows can be previously measured in the DC device during tests before the marketing of the DC device.

For example, the determination of the coefficient A _n relative to the frequency band BF _n takes into account a collision avoidance mechanism relating to the CSMA / CA protocol ("Carrier Sense Multiple Access with Collision Avoidance") of the media access control (MAC), a mechanism based on a principle of reciprocal acknowledgments between the device and the scrambler transmitting signals in the frequency band BF _n .

When determining an evaluation score for a given frequency band BF _n in step E5 as described below, the coefficient A _n associated with the given frequency band BF _n is equal to 0.4 either the given frequency band BF _n . As an example for a given frequency band BF _n , the coefficients A _n-4 to A _{n + 4} respectively associated with frequency bands BF _n-4 to BF _{n + 4} are respectively 0.2; 0.9; 0.9; 0, 8; 0.4; 0.5; 0.6; 0.9 and 0.3. If the given frequency band is the band BF ₆ , then the associated coefficient A ₆ is 0.4 and the coefficient A ₅ associated with the band BF ₅ is 0.8. Similarly, if the given frequency band is the band BF ₈ , then the associated coefficient A ₈ is 0.4 and the coefficient A ₇ associated with the band BF ₇ is 0.8.

In step E1, the device DC checks whether a frequency band BF _n has been manually selected by a user.

If a frequency band has already been selected, then the MSB frequency band selection module of the device allocates the selected frequency band to a communication channel for transmitting and receiving signals and the method ends as indicated in a step F .

If no frequency band has been previously selected, the DC device scans the N = 13 available frequency bands to measure a total received signal power and a noise power in each of the frequency bands BF _n in step E2 according to substeps E21 and E22.

In substep E21, for each frequency band BF _n , the device DC searches for the presence of identifiable scramblers BR1 which are under the radio coverage of the access point including the DC device and which transmit signals in the frequency band. BF _n .

For each frequency band BF _n , the MRP power receiving module determines a received signal power for each of the detected BR1 jammers. for example, depending on the power of a beacon signal emitted by each of the jammers. The MRP module defines an indicator IND _n received power RSSI ("Received Signal Strength Indicator" in English) which takes values between a minimum value for example equal to "0" and a maximum value for example equal to "100" in function of the power of a signal received from a scrambler BR1 detected in the frequency band BF _n . If the indicator IND _n is equal to "0", the device DC receives no signal, and if the indicator IND _n is equal to "100", the device receives in the frequency band BF _n a signal with a power greater than a maximum power threshold. This indicator is for example evaluated at the physical layer level to indicate the signal power received by the device using a Physical Layer Control Protocol (PCLP) header in PPDU protocol data units ("PCLP Protocol"). Data Unit "in English).

The power reception module MRP associates with each frequency band BF _n a number N _n of jammers BR1 which are under the radio coverage of the access point including the DC device and which emit signals in the frequency band BF _n .

The power receiving module MRP furthermore associates each frequency band BF _{n with} a parameter S _n equal to the largest of the IND indicator _n relative to the frequency band BF _n . The parameter S _n therefore depends on the maximum power received in the frequency band BF _n .

For example, the device DC detects the signals emitted by two jammers BR1 by means of beacon signals transmitted by them for the frequency band BF ₇ and determines two indicators of power InD ₇ relating to the two detected jammers. If the IND indicators ₇ are 30 and 45, the parameter S ₇ associated with the frequency band BF ₇ is equal to 45.

In substep E22, the MRP power receiving module of the DC device determines a noise power PB _n for each frequency band BF _n . For example, the device DC extracts the noise power from standard measurements such as the measurement of a received signal-to-noise ratio, the received signal being for example the set of beacon signals emitted by the interferers BR1 in the frequency band. BF _n . The noise power PB _n may be related to the sensitivity of a receiver included in the DC device with respect to the quality of the received signal and may relate to signals other than the beacon signals and transmitted in particular by one or more BR2 jammers. .

In step E3, the power receiving module MRP compares each noise power PB _n associated with a frequency band BF _n with a predefined threshold SP, for example equal to -50 dBm.

If all the frequency bands BF _n are respectively associated with noise powers PB _n greater than the predefined threshold, the frequency band selection module MSB selects the frequency band BF _n associated with the lowest noise power PB _n and allocates the BF band _n to a communication channel for transmitting and receiving signals in step E4.

If at least one frequency band BF _n is associated with a noise power PB _n less than the predefined threshold SP, the evaluation module MEV assigns at step E5 an evaluation score F _n to each frequency band BF _n associated with a noise power PB _n less than the predefined threshold SP. The evaluation score F _n is determined for each given frequency band BF _n as a function of the coefficients A _n-4 to A _{n + 4} and the parameters S _n-4 to S _{n + 4} associated with the given frequency band BF _n and frequency bands partially superimposed on the given frequency band BF _n . More particularly, the parameters S _n-4 to S _{n + 4} are weighted respectively by the coefficients A _n-4 to A _{n + 4} .

Each given frequency band BF _n is partially superimposed on at most eight adjacent frequency bands BF _n-4 to BF _{n + 4} and is associated with the evaluation score F _n defined by the following relation: $${\mathrm{F}}_{\mathrm{not}}\mathrm{=}{\mathrm{AT}}_{\mathrm{not}\mathrm{-}\mathrm{4}}{\mathrm{S}}_{\mathrm{not}\mathrm{-}\mathrm{4}}\mathrm{+}{\mathrm{AT}}_{\mathrm{not}\mathrm{-}\mathrm{3}}{\mathrm{S}}_{\mathrm{not}\mathrm{-}\mathrm{3}}\mathrm{+}{\mathrm{AT}}_{\mathrm{not}\mathrm{-}\mathrm{2}}{\mathrm{S}}_{\mathrm{not}\mathrm{-}\mathrm{2}}\mathrm{+}{\mathrm{AT}}_{\mathrm{not}\mathrm{-}\mathrm{1}}{\mathrm{S}}_{\mathrm{not}\mathrm{-}\mathrm{1}}\mathrm{+}{\mathrm{NOT}}_{\mathrm{not}}{\mathrm{AT}}_{\mathrm{not}}{\mathrm{S}}_{\mathrm{not}}\mathrm{+}{\mathrm{AT}}_{\mathrm{not}\mathrm{+}\mathrm{1}}{\mathrm{S}}_{\mathrm{not}\mathrm{+}\mathrm{1}}+{\mathrm{AT}}_{\mathrm{not}\mathrm{+}2}{\mathrm{S}}_{\mathrm{not}\mathrm{+}2}\mathrm{+}{\mathrm{AT}}_{\mathrm{not}\mathrm{+}\mathrm{3}}{\mathrm{S}}_{\mathrm{not}\mathrm{+}\mathrm{3}}\mathrm{+}{\mathrm{AT}}_{\mathrm{not}\mathrm{+}\mathrm{4}}{\mathrm{S}}_{\mathrm{not}\mathrm{+}\mathrm{4}}\mathrm{.}$$

When identifiable scramblers BR1 emit signals in the given frequency band BF _n , the coefficient A _n associated with the frequency band BF _n is weighted by the number N _n of the identifiable scramblers BR1 in the band BF _n .

For example, the evaluation score F ₁ associated with the frequency band BF ₁ depends on the coefficients A ₁ and A ₂ , A ₃ , A ₄ and A ₅ and the parameters S ₁ and S ₂ , S ₃ , S ₄ and S ₅ associated respectively with the frequency band BF ₁ and the adjacent frequency bands BF ₂ , BF ₃ , BF ₄ and BF ₅ .

According to another example, the evaluation score F ₇ associated with the frequency band BF ₇ depends on the coefficients A ₃ , A ₄ , A ₅ , A ₆ , A ₇ , A ₈ , A ₉ , A ₁₀ and A ₁₁ . and parameters S ₃ , S ₄ , S ₅ , S ₆ , S ₇ , S ₈ , S ₉ , S ₁₀ and S ₁₁ associated with the frequency band BF ₇ and with adjacent frequency bands BF ₃ , BF ₄ , BF ₅ , BF ₆ , BF ₈ , BF ₉ , BF ₁₀ and BF ₁₁ .

According to yet another example, only the frequency bands BF ₆ and BF ₇ are associated with noise power levels PB ₆ and PB ₇ less than the predefined threshold SP and only the evaluation scores F ₆ and F ₇ are determined.

In step E6, the frequency band selection module MSB selects the frequency band BF _n having the evaluation score F _n minimum among the evaluation scores determined previously. The MSB module allocates the selected frequency band to a communication channel for transmitting and receiving signals.

If several evaluation scores associated with frequency bands are identical, then the MSB module selects the frequency band from among these with the lowest center frequency.

$${\mathrm{F}}_2={\mathrm{A}}_{2-1}\times {\mathrm{S}}_1=0,8\times 55=44;$$

$${\mathrm{F}}_3={\mathrm{A}}_{3-2}\times {\mathrm{S}}_1+{\mathrm{A}}_{3+4}\times {\mathrm{S}}_7=0,9\times 55+0,3\times 45=63;$$

$${\mathrm{F}}_4={\mathrm{A}}_{4-3}\times {\mathrm{S}}_1+{\mathrm{A}}_{4+3}\times {\mathrm{S}}_7=0,9\times 55+0,9\times 45=90;$$

$${\mathrm{F}}_5={\mathrm{A}}_{5-4}\times {\mathrm{S}}_1+{\mathrm{A}}_{5+2}\times {\mathrm{S}}_7=0,2\times 55+0,6\times 45=38;$$

$${\mathrm{F}}_6={\mathrm{A}}_{6+1}\times {\mathrm{S}}_7=0,5\times 45=22,5;$$

$${\mathrm{F}}_7={\mathrm{N}}_2\times {\mathrm{A}}_7\times {\mathrm{S}}_7=2\times 0,4\times 45=36;$$

$${\mathrm{F}}_8={\mathrm{A}}_{8-1}\times {\mathrm{S}}_7=0,8\times 45=36;$$

$${\mathrm{F}}_9={\mathrm{A}}_{9-2}\times {\mathrm{S}}_7=0,9\times 45=40,5;$$

$${\mathrm{F}}_{10}={\mathrm{A}}_{10-3}\times {\mathrm{S}}_7=0,9\times 45=40,5;$$

$${\mathrm{F}}_{11}={\mathrm{A}}_{11-4}\times {\mathrm{S}}_7=0,2\times 55=9;$$

$${\mathrm{F}}_{12}=0;$$

et $${\mathrm{F}}_{13}=0.$$

According to an exemplary embodiment, the device DC detects N ₁ = 1 jammer BR1 for the frequency band BF ₁ and determines a power indicator IND ₁ equal to 55. In addition, the device DC detects N ₇ = 2 jammers BR1 for the BF frequency band ₇ and determines two IND ₇ power indicators equal to 45 and 30. The DC device then associates parameters S ₁ and S ₇ respectively equal to 55 and 45 respectively to the frequency bands BF ₁ and BF ₇ . The other parameters S _n , for n ≠ 1 and n ≠ 7, are zero. As described in an example above, for a given frequency band BF _n , the coefficients A _n-4 to A _{n + 4} respectively associated with the frequency bands BF _n-4 to BF _{n + 4} are respectively 0.2; 0.9; 0.9; 0.8; 0.4; 0.5; 0.6; 0.9 and 0.3. The N = 13 evaluation scores F _n associated respectively with N = 13 bands of frequency BF _n have the following values, each band BF _n having a noise power lower than the threshold SP: $${\mathrm{F}}_1={\mathrm{NOT}}_1\times {\mathrm{AT}}_1\times {\mathrm{S}}_1=1\times 0,4\times 55=22;$$

$${\mathrm{F}}_2={\mathrm{AT}}_{2-1}\times {\mathrm{S}}_1=0,8\times 55=44;$$

$${\mathrm{F}}_3={\mathrm{AT}}_{3-2}\times {\mathrm{S}}_1+{\mathrm{AT}}_{3+4}\times {\mathrm{S}}_7=0,9\times 55+0,3\times 45=63;$$

$${\mathrm{F}}_4={\mathrm{AT}}_{4-3}\times {\mathrm{S}}_1+{\mathrm{AT}}_{4+3}\times {\mathrm{S}}_7=0,9\times 55+0,9\times 45=90;$$

$${\mathrm{F}}_5={\mathrm{AT}}_{5-4}\times {\mathrm{S}}_1+{\mathrm{AT}}_{5+2}\times {\mathrm{S}}_7=0,2\times 55+0,6\times 45=38;$$

$${\mathrm{F}}_6={\mathrm{AT}}_{6+1}\times {\mathrm{S}}_7=0,5\times 45=22,5;$$

$${\mathrm{F}}_7={\mathrm{NOT}}_2\times {\mathrm{AT}}_7\times {\mathrm{S}}_7=2\times 0,4\times 45=36;$$

$${\mathrm{F}}_8={\mathrm{AT}}_{8-1}\times {\mathrm{S}}_7=0,8\times 45=36;$$

$${\mathrm{F}}_9={\mathrm{AT}}_{9-2}\times {\mathrm{S}}_7=0,9\times 45=40,5;$$

$${\mathrm{F}}_{10}={\mathrm{AT}}_{10-3}\times {\mathrm{S}}_7=0,9\times 45=40,5;$$

$${\mathrm{F}}_{11}={\mathrm{AT}}_{11-4}\times {\mathrm{S}}_7=0,2\times 55=9;$$

$${\mathrm{F}}_{12}=0;$$

and $${\mathrm{F}}_{13}=0.$$

The two frequency bands BF ₁₂ and BF ₁₃ have noise power levels PB ₁₂ and PB ₁₃ less than the predefined threshold SP and an assessment score that is minimal among the different evaluation scores. The MSB module then selects the frequency band BF ₁₂ since it has a lower center frequency than that of the frequency band BF ₁₂ .

In a variant, the evaluation module MEV assigns at a step E5bis an evaluation score F _n to each frequency band BF _n , whatever the noise power PB _n associated with the frequency band BF _n , c ' that is, even if the noise power PB _n is greater than the predefined threshold SP. The evaluation score F _n is determined for each given frequency band BF _n as in step E5.

Then at a step E6bis, the MSB frequency band selection module determines the score assessment score among the evaluation scores previously determined. The MSB module compares the noise power PB _n associated with the frequency band BF _n with the lowest evaluation score at the threshold SP.

If the noise power PB _n is less than the threshold SP, the module MSB selects the frequency band BF _n and allocates the latter to a communication channel for transmitting and receiving signals.

If the noise power PB _n is greater than the threshold SP, the module MSB compares the noise power associated with the frequency band with the lowest evaluation score following the threshold SP. Similarly, if the previous noise power is below the threshold SP, the frequency band is selected by the DC device. This process can be repeated until a noise power lower than the threshold SP is found.

The device DC thus selects the frequency band BF _n associated with a noise power PB _n less than the threshold SP, which has the evaluation score F _n minimal.

The invention described herein relates to a method and a device for selecting a frequency band. According to one implementation, the steps of the method of the invention are determined by the instructions of a computer program incorporated in the device such as the communication device DC. The program comprises program instructions which, when said program is executed in a processor of the device whose operation is then controlled by the execution of the program, carry out the steps of the method according to the invention.

Accordingly, the invention also applies to a computer program, in particular a computer program recorded on or in a computer readable recording medium and any data processing device, adapted to implement the computer program. 'invention. This program can use any programming language, and be in the form of source code, object code, or intermediate code between source code and object code such as in a partially compiled form, or in any other form desirable to implement the method according to the invention.

The recording medium may be any entity or device capable of storing the program. For example, the medium may comprise storage means on which the computer program according to the invention is recorded, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or a USB key, or magnetic recording means, for example a diskette (floppy disc) or a hard disk.

On the other hand, the recording medium may be a transmissible medium such as an electrical or optical signal, which may be conveyed via an electrical or optical cable, by radio or by other means. The program according to the invention can in particular be downloaded to an Internet type network.

Alternatively, the recording medium may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the method according to the invention.

Claims (12)

A method for selecting a frequency band in a telecommunications network having a plurality of partially superposed frequency bands (BF _n ), comprising a measurement (E21) of at least one received signal power in each frequency band, characterized in that the measurement comprises a determination (E21) of a maximum received signal power in each frequency band, and that the method comprises the following steps: an association (E21) of parameters (S _n ) respectively to the frequency bands (BF _n ), each parameter (S _n ) being determined as a function of the maximum signal power received in the respective frequency band, an allocation (E5) of scores (F _n ) to at least some of the frequency bands (BF _n ), a score being assigned to a frequency band according to the parameters associated with said frequency band and the frequency bands partially superimposed on said frequency band, and a selection (E6) of the frequency band having a minimum score compared to the scores assigned to the frequency bands. The method according to claim 1, wherein the parameter (S _n ) associated with a respective frequency band (BF _n ) depends on the largest of the identifiable jammer signal strengths (BR1) received in the respective frequency band. Method according to claim 1, comprising a determination (E22) of a noise power (PB _n ) for each frequency band (BF _n ), a score (F _n ) being assigned to each frequency band only (BF _n ) whose determined noise power is below a threshold. A method according to claim 1, comprising determining (E22) a noise power (B _n ) for each frequency band (BF _n ), a score (F _n ) being assigned to each frequency band, and the band of selected frequency with the minimum score compared to the assigned scores having a determined noise power below a threshold. A method according to any one of claims 1 to 4, wherein the parameters (S _n ) respectively associated with the frequency bands (BF _n ) are respectively weighted by coefficients (A _n ) for the assignment of a score ( F _n ) at each frequency band, each coefficient associated with a frequency band depending on a maximum bit rate in the frequency band to which the score is allocated in the presence of jamming signals in the frequency band with which the signal is associated. coefficient on a maximum rate in the frequency band to which the score is allocated in the absence of interference signals. A method according to any one of claims 1 to 5, wherein the parameter (S _n ) associated with a frequency band (BF _n ) is weighted by a number (N _n ) of equipment (BR1) transmitting signals in said frequency band for assigning a score (F _n ) to said frequency band. A method according to any one of claims 1 to 6, wherein the frequency bands have respective center frequencies spaced apart from each other over a given frequency interval and have the same bandwidth, and the number of bands of frequency partially superimposed on a frequency band is substantially equal to twice the ratio of the frequency bandwidth over the given frequency range. A method according to any one of claims 1 to 7, wherein the telecommunications network is a wireless local area network. An apparatus for selecting a frequency band in a telecommunications network having a plurality of partially superimposed frequency bands (BF _n ), comprising means (MRP) for measuring at least one power of a received signal in each frequency band, characterized in what the means for measuring (MRP) is able to determine a maximum signal power received in each frequency band, and in that the device comprises: means (MRP) for associating parameters (S _n ) respectively with the frequency bands (BF _n ), each parameter (S _n ) being determined as a function of the maximum received signal power in the respective frequency band, means (MEV) for assigning scores (F _n ) to at least some of the frequency bands (BF _n ), a score being assigned to a frequency band according to the parameters associated with said band of frequency and frequency bands partially superimposed on said frequency band, and means (MSB) for selecting the frequency band having a minimum score in relation to the scores assigned to the frequency bands. Device according to claim 9, included in an access point of a wireless local area network. A computer program adapted to be implemented in a device (DC) for selecting a frequency band in a telecommunications network having a plurality of partially superposed frequency bands (BF _n ), said program comprising instructions which, when the program is loaded and executed in said device (DC), perform a measurement (E21) of at least one power of a signal received in each frequency band, said program being characterized in that the measurement comprises a determination (E21) d a maximum received signal power in each frequency band, and the program instructions furthermore realize: an association (E21) of parameters (S _n ) respectively to the frequency bands (BF _n ), each parameter (S _n ) being determined as a function of a maximum signal power received in the respective frequency band, an allocation (E5) of scores (F _n ) to at least some of the frequency bands (BF _n ), a score being assigned to a frequency band according to the parameters associated with said frequency band and the frequency bands partially superimposed on said frequency band, and a selection (E6) of the frequency band having a minimum score compared to the scores assigned to the frequency bands. A recording medium readable by a device on which a computer program is recorded for selecting a frequency band in a telecommunications network having a plurality of partially superimposed frequency bands (BF _n ), said program including instructions for a measurement ( E21) of at least one power of a signal received in each frequency band, characterized in that the measurement comprises a determination (E21) of a maximum signal power received in each frequency band, and the program of computer has instructions for performing further the following steps: an association (E21) of parameters (S _n ) respectively to the frequency bands (BF _n ), each parameter (S _n ) being determined as a function of a maximum signal power received in the respective frequency band, an allocation (E5) of scores (F _n ) to at least some of the frequency bands (BF _n ), a score being assigned to a frequency band according to the parameters associated with said frequency band and the frequency bands partially superimposed on said frequency band, and a selection (E6) of the frequency band having a minimum score compared to the scores assigned to the frequency bands.

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